An overweight vehicle is thought to have caused the collapse early on Nov. 18 of a roughly 150-meter-long steelwork suspension bridge in Mirepoix-sur-Tarn, a French village 30 km northeast of Toulouse.

Carrying five bus lines and five light-rail lines, the Steel Bridge crossing the Willamette River in downtown Portland has significant public transit clout. But it also carries with it some concerns.